1. Field of the Invention
The present invention relates to a process for removing metals such as, for example, sodium, potassium, calcium, iron, nickel, etc., from vinylphenol polymers, i.e., vinylphenol homopolymers, vinylphenol copolymers, modified polymers thereof, derivatives thereof, etc., by contacting a solution thereof with a strongly acidic cation exchange resin.
2. Description of the Prior Art
It is known that vinylphenol can be manufactured by dehydration of acetoxyphenylmethyl carbinol, decomposition of hydroxycinnamic acid by decarboxylation reaction, dehydrogenation of ethylphenol, or the like. It is also known that vinylphenol monomers manufactured by these processes can be polymerized or copolymerized in the presence of a cation or a radical polymerization initiator to produce vinylphenol-containing polymers (hereinafter referred to simply as vinylphenol polymers).
A number of products, processes for manufacturing thereof, and processes relating to the use of vinylphenol polymers are known in the art, including a process for producing a modified vinylphenol polymer product having a superior light transmittance by hydrotreating a vinylphenol polymer (Japanese patent Laid-open No. Hei 1 (1989)-103604, a process for producing a modified vinylphenol polymer product having excellent flexibility by a heat fusing reaction of a vinylphenol polymer or a mixture of a vinylphenol polymer and a novolak-type phenol resin (Japanese Patent Laid-open No. Sho 60 (1985)-58407, No. Sho 60 (1985)-81228), processes for manufacturing various ester or ether derivatives by the reaction of the hydroxy group of vinylphenol polymers, processes for the manufacture of various nuclear substituted derivatives of vinylphenol polymers, and the like.
These vinylphenol polymers generally contain metals such as sodium, iron, and the like originating from raw materials and auxiliary materials used in the manufacturing processes. Furthermore, it is very difficult to avoid contamination of vinylphenol polymers with metals during the manufacturing processes from materials from which the manufacturing apparatus is constructed, or from foul in the manufacturing apparatus as well as contaminants coming from the environment. Thus, contamination of vinylphenol polymers with metal impurities such as sodium and iron has been unavoidable according to conventional manufacturing processes of vinylphenol polymers. No process for removing these metal impurities has been known in the art heretofore.